The oxidation of carbohydrates by various nitroxide-mediating reagents are known in the art.
The use of nitroxyl radicals and nitrosonium salts to produce aldehydes and carboxylic acids particularly applied to the selective oxidation of primary alcohols in various carbohydrates to carbonyl and/or carboxylic acids has been reported. See “Selective Oxidation of Primary Alcohols Mediated by Nitroxyl Radical in Aqueous Solution. Kinetics and Mechanism” by A. E. J. de Nooy and A. C. Bessemer, in Tetrahedron, Vol. 51, No. 29, 1995, pp. 8023–8032; WO 95/07303 dated Mar. 16, 1995 to Bessemer et al.; and “Oxidation of Primary Alcohol Groups of Naturally Occurring Polysaccharides with 2,2,6,6-Tetramethyl-1-piperidine Oxoammonium Ion” by P. S. Chang and J. F. Robyt in J. Carbohydrate Chemistry, 15(7), 1996, pp. 819–830.
Unfortunately, many of these processes require the use of environmentally harmful chemical reagents. In addition, most oxidative methods are not selective and cause degradation of the carbohydrate and the formation of excess carboxyl groups. Excess carboxyl groups reduce the degree of aldehyde substitution and affect the cationic/anionic balance of the functional groups on the product. This is particularly undesirable in polysaccharides which are used in or as pulp suitable for papermaking and absorbent applications.
Accordingly, there remains a need for an environmentally friendly selective oxidation route to produce carbohydrate aldehyde derivatives having a suitable aldehyde content.